Abstract: [Objective] Studies were conducted to use biotechnology for multiplication of selected superior Cryptomeria clones, in order to provide theoretical and technical basis for multiplication of superior Cryptomeria clones and preservation of the genetic materials of Cryptomeria clones.[Method] Young shoots of different Cryptomeria clones were taken as explants were sterilized and treated with different hormones with different concentrations in different growing media, and an orthogonal design L₉(3⁴) was used to analyze their interaction. Bud multiplication of six Cryptomeria clones and rooting ability of three clones were compared to analyze differences among clones.[Result] The results showed that all the six clones formed multiple shoots and there were great differences in bud multiplication among different clones. The multiplication coefficient of clone ‘Jing 1’ reached 5.00 on average. Besides, clones ‘011’, ‘3’, and ‘7’ also displayed superiority. On the other hand, the multiplication coefficients of clone ‘59’ and ‘68’ were 3.10 and 3.28 respectively, indicating poor bud multiplication and growth. The results showed that the interaction between 6-BA and NAA and 6-BA alone had a great influence on the multiplication coefficients of the clone ‘Jing 1’. However, the influence of NAA was not significant within a certain range of concentration. Significant influences on bud multiplication coefficient were found between 6-BA, NAA and their interaction in other 5 clones ‘011’, ‘3’, ‘59’, ‘70’ and ‘68’. There were differences among hormone types which play a leading role in bud multiplication of different clones. The main factor in the multiplication of clone ‘011’ ‘Jing 1’, ‘3’ and ‘70’ was 6-BA while the main factor in the multiplication of clone ‘59’ and ‘68’ was NAA. Three clones that produced adventitious roots displayed significant difference in rooting rate among clones, among the three clones, the clone ‘011’ showed the highest levels in rooting rate, number of average roots, the ability of forming adventitious roots, and the length of most roots of the clone extended from 2 to 3 cm. The rooting rate of clone ‘70’ took the second place with the length of roots extending from 2.5 to 3.5 cm. In contrast, clone ‘3’ had root length more than 4 cm but the lower rooting rate (75.6%).[Conclusion] By analyzing differences in bud multiplication and root induction among Cryptomeria clones, it indicated that the capacity of bud multiplication and rooting ability were genetically controlled. The regeneration capacity through tissue culture of different Cryptomeria clones requires specific types of culture media, and hormones and their respective proportions.

Key words: Cryptomeria, clone, regeneration capacity, bud multiplication, rooting ability